A debilitating disease has struck elk populations across the Northwest. Now, researchers have linked several types of bacteria to lesions on elk hooves.
Elk hoof disease, scientifically known as treponeme-associated hoof disease or TAHD, is pretty much what it sounds like. It’s marked by painful lesions that make it hard for wild elk to move like normal. While it’s not fatal, the deformities can lead to starvation and can make elk more susceptible to predators and hunters. It’s highly infectious among elk but doesn’t affect people.
“This is a relatively new disease syndrome, in the grand scheme of things,” said Liz Goldsmith, a veterinary pathologist and lead author of this new study. “We’re still very much in the early phases of trying to understand what causes it.”
Goldsmith’s new research out of Washington State University’s College of Veterinary Medicine found multiple bacteria are associated with the disease. In addition, those bacteria can be found in different areas throughout the disease’s range – not just where the disease is most prevalent.
“ The better we can understand the bacterial populations within these lesions, the better we can understand what's actually causing them,” Goldsmith said.
That’s important because understanding the disease could play a key role in elk management. There is currently no treatment or vaccine for the disease in wild elk.
“ (Studying this disease) really has implications on the ground, for long-term investigation of the disease, as well as giving more information to wildlife managers who are out there making decisions,” Goldsmith said.
In Washington, most of the elk hoof disease has been found in the southwestern part of the state.
In Oregon, most cases were initially found in the northwestern part of the state. A few scattered cases have been identified in northeastern and southwestern Oregon.
The disease was first confirmed in Idaho in 2019.
Wildlife leaders ask hunters to report sightings of limping or dead elk with hoof deformities. In addition, they suggest hunters leave elk hooves in the field.
“ This research would not be possible without hunters and is definitely something that hunters across the West are concerned about,” Goldsmith said.
For Goldsmith’s study, scientists collected normal and abnormal hooves, with the help of state, federal and tribal wildlife management agencies. In total, they collected samples from nearly 130 free-ranging elk.
The samples came from places where the disease is widespread, where it’s identified spradically and where it hasn’t been found at all.
In the lab, researchers examined the hooves with the naked eye, took tissue samples from the space between the toes, known as the interdigital space, and looked at the tissues under a microscope.
Elk hooves aren’t the cleanest of samples, so they used genetic sequencing to identify the bacteria involved.
“The consistent presence of Treponema and Mycoplasma in TAHD lesions suggests these bacteria may be working together, and that the disease is driven by a complex microbial community rather than a single pathogen,” Goldsmith said in a news release.
Next, the study wanted to learn more about the geographic range of the disease. It’s a bit of a mystery, Goldsmith said, because there are areas where the elk hoof disease is very widespread and other places where it’s very sporadic. Researchers thought that could be explained by how much bacteria was out there.
However, surprisingly, she found the bacteria everywhere. Researchers don’t yet know what that means.
“ So for future research, there are lots of different options to look into to explain why we might be seeing this out in the field,” she said.
Researchers are also conducting further studies to better understand where the bacteria is within the lesions, which could show how the bacteria interacts and helps the disease’s progression. They hope to eventually develop rapid diagnostic tests to help wildlife managers.
